Canine stress syndrome/malignant hyperthermia susceptibility: calcium-homeostasis defect in muscle and lymphocytes.
This study provides the first comprehensive characterisation of the calcium (Ca) homeostasis defects found in muscle and lymphocytes of a malignant hyperthermia (MH)-susceptible dog. Novel findings regarding this dog are reported, compared to controls. First, a canine stress syndrome occurs, analogous to the porcine stress syndrome; susceptibility can be identified by exercise challenge testing. Secondly, caffeine causes Ca release from muscle sarcoplasmic reticulum in a greater amount and at a greater rate. Thirdly, there is a compensatory increase in Ca sequestration by sarcoplasmic reticulum. Fourthly, lymphocytes have lower cytosolic-free Ca and a greater ability to prevent Ca increase. Halothane increases Ca by a greater amount and rate. Fifthly, muscle is more resistant to the contracture-producing effects of caffeine, as occurs in the non-rigid variant of MH susceptibility in man. This resistance, despite increased caffeine-induced release through the Ca channel, may be attributable to increased Ca sequestration by sarcoplasmic reticulum. Finally, erythrocyte osmotic fragility and creatine kinase tests fail to distinguish between the MH-susceptible dog and controls.
O'Brien
P J
PJ
Department of Pathology, University of Guelph, Ontario Veterinary College, Canada.
Pook
H A
HA
Klip
A
A
Britt
B A
BA
Kalow
B I
BI
McLaughlin
R N
RN
Scott
E
E
Elliott
M E
ME
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004283:Dog Diseases / Q000209:etiology / Q000378:metabolism*; D004285:Dogs; D005260:Female; D006221:Halothane / Q000633:toxicity; D006706:Homeostasis; D008214:Lymphocytes / Q000378:metabolism / Q000648:ultrastructure; D008305:Malignant Hyperthermia / Q000209:etiology / Q000378:metabolism / Q000662:veterinary*; D009132:Muscles / Q000378:metabolism / Q000648:ultrastructure; D009996:Osmotic Fragility; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013312:Stress, Physiological / Q000150:complications / Q000662:veterinary*
D002118:Calcium; D006221:Halothane